Gordon Brown has called for Brexit to be delayed by a year to give the public the final say and rescue Britain from its political crisis.

The former Prime Minister said so-called “citizens’ assemblies” should be formed across the UK to discuss various options, before a People’s Vote is then held if it is established the situation has changed.

His proposal came as the Government announced what has been dubbed the “moment of truth,” the day when MPs debate and vote on Mrs May’s Plan B and their preferred alternatives: Tuesday January 29.

It also came as the PM and her senior ministers held “constructive” daylong private meetings with a range of MPs, including Labour ones, who defied Jeremy Corbyn’s appeal for them to boycott the cross-party talks, branding them a “stunt”.

It emerged during those meetings that Whitehall officials had drawn up an illustrative paper to inform discussions, which estimated it would take more than a year to organise any People’s Vote.

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But Conservative MP Dominic Grieve, a leading supporter of the People's Vote campaign, said the suggested timetable was "simply wrong" and it could be carried out quickly within a limited time extension of Article 50.

"It is neither helpful nor right to have misleading information of this kind put out," insisted the former Attorney General.

Addressing a packed pro-EU meeting in Edinburgh, Mr Brown said the largest parliamentary defeat inflicted on Mrs May’s Brexit Plan had make Britain’s democracy look “dysfunctional,” and insisted he had never known a time when Westminster had been so paralysed for so long.

“It is the lethal combination of a deadlocked parliament, an ever-more divided country and the mounting distrust between Parliament and people that makes me fear for our cohesion,” declared the former Labour leader.

He argued that it was an illusion that a “one-off improvisation” could solve the problem, insisting: “Our crisis is so profound that Parliament cannot now solve it on its own.”

Mr Brown said Britain was now more divided than during the three-day week of the 1970s, the miners’ strike of the 1980s and the poll tax of the 1990s. With distrust of the political system so high, he said it was now time to engage the country.

He added: “I propose we negotiate with Europe to extend Article 50 for one year not as a delaying tactic but for a purpose – that we agree, and the European Union accepts, a unique democratic innovation – the convening of nationwide citizens‘ assemblies.”

These would take place across each region and nation of the UK, looking at all the issues thrown up by Brexit, including immigration and sovereignty. Mr Brown said they would be modelled on similar schemes which took place before the Irish abortion referendum.

The results of the citizens’ assemblies would be discussed by MPs and a new proposal made that would be negotiated with the EU.

The former PM noted: “As someone who spent years in government negotiating with them I feel confident they would accept. And then, if it is established that the situation has changed, give the British people the right to the final say.”

He added: “Trust cannot be rebuilt without the widest possible involvement of citizens and communities as well as politicians. The people of Britain must be brought back into this debate.”

Mr Brown compared the situation to the space race between Russia and America – two Cold War rivals who eventually cooperated with the establishment of the International Space Station.

He said: “If we can find a way, surely, to cooperate in outer space, in an area where there was a space race to the finish for 30 years, surely we can find a way to base a new relationship with Europe on cooperation and international outlook.”

Mr Brown’s remarks came as Conservative MP Nick Boles, the former Skills Minister, began a drive at Westminster to get MPs’ support to extend Article 50 for nine months.

Claiming there were as many as 400 MPs ready to back a soft Brexit, he said: “The Bill would say this that if the PM has not secured a compromise bill and got it through Parliament by the end of the first week of March then she would be legally mandated to write to the EU and ask for a nine-month extension to Article 50; that would stop no-deal Brexit happening.”

In Brussels, EU officials are said to be considering a delay to Brexit until 2020 after France and Germany indicated their willingness to extend withdrawal negotiations because of the UK’s political crisis.

However, No 10 made clear the Government had not raised extending the Article 50 process with the European Commission because it was not Government policy. When it was suggested the Mrs May’s spokesman that if the EU27 offered to facilitate an extension, the UK would refuse the offer, she replied: “Correct.”

Meanwhile, Mrs May clashed with Mr Corbyn over the cross-party talks.

In a letter to the Labour leader, she claimed it was "impossible" for the Government to rule out a no-deal Brexit, which he laid down as a pre-condition to his engaging in the Brexit talks.

The PM insisted it was "not within the Government's power" to guarantee a no-deal as this could be done only by securing Parliament's approval for a withdrawal agreement or by overturning the result of the 2016 referendum, something she was not prepared to do.

Earlier, Mr Corbyn emailed Labour colleagues, saying any starting point for talks must be that the threat of a disastrous no-deal outcome was ruled out, noting how this was the position that “has now been adopted by the First Minister of Scotland, Nicola Sturgeon”.

He added: "I urge colleagues to respect that condition and refrain from engagement with the Government until no-deal is taken off the table."

In her letter of response, Mrs May took the Labour leader to task, saying: "You have always believed in the importance of dialogue in politics. Do you really believe that, as well as declining to meet for talks yourself, it is right to ask your MPs not to seek a solution with the Government?”

She added: "My door remains open to a meeting without preconditions so that we, as Prime Minister and Leader of the Opposition, can talk and see if we can begin to find a way forward for our country on Brexit. I sincerely urge you to accept."

Mr Corbyn also came under fire for not engaging in the cross-party talks from Labour critic Mike Gapes, who tweeted: "Apparently Corbyn is prepared to hold talks with Hamas, Hezbollah, Assad and Iran without preconditions. But not with the UK Prime Minister. Why?”

Tony Blair, the former PM, argued Mr Corbyn was wrong to refuse to meet Mrs May, saying: "If, in a moment of national crisis, the Prime Minister asks the Leader of the Opposition to come and talk, of course he should."

Among those who did engage in the talks were senior Labour backbenchers Hilary Benn and Yvette Cooper, Liberal Democrats Jo Swinson and Alistair Carmichael, various Tory Eurosceptics such as David Davis, Mark Francois and Peter Bone, as well as their Remain colleague Nicky Morgan and the Democratic Unionist leaders Arlene Foster and Nigel Dodds.

Emerging from Downing Street, Ms Foster said the issue of the Irish backstop needed to be dealt with "in a very clear way" if Brexit negotiations were to make progress.

Ms Cooper said: "The most important thing now is that the Government actually listens and it doesn't just think that a defeat that was that huge can simply be dismissed."

Green MP Caroline Lucas said the PM had shown little sign she was ready for compromise, noting: "I'm not convinced she's willing to loosen any of the red lines she's set herself."

Early in a speech in the marginal Conservative seat of Hastings, Mr Corbyn claimed the PM seemed unable to grasp the fact that her Withdrawal Agreement was now "dead" following the record 230-strong Commons defeat.

"She seems to be prepared to send the country hurtling towards a cliff edge," declared the Labour leader. "To get a deal that can command a majority in Parliament, Theresa May has to ditch the red lines and get serious about proposals for the future."

But Brandon Lewis, the Tory Chairman, accused Labour of "trying to frustrate and avoid Brexit".

And Sir Vince Cable, the Liberal Democrat leader, accused Mr Corbyn of playing "party political games," stressing that his party would no longer join Labour in no-confidence votes in the Government.

"I believe other parties are taking the same view; it's time Mr Corbyn got off the fence and made his position plain," added the Twickenham MP.

In other developments –

*Chancellor Philip Hammond was branded "treacherous" by a Tory backbencher after telling business leaders a no-deal Brexit could be "taken off the table" and Article 50 "rescinded". One Cabinet minister branded him a "rogue element" and accused Mr Hammond of trying to "bounce" colleagues into abandoning the possibility of a no-deal outcome.

*Michael Gove’s deputy at the Department for the Environment, George Eustace, let slip the Secretary of State was, in the cross-party talks, pushing for a "customs arrangement" after Brexit.

*Defence Secretary Gavin Williamson announced military reservists had been put on standby for up to a year of permanent service to handle the possible fall-out from a no-deal Brexit, they will make up around 10 per cent of the 3,500 armed forces personnel held at readiness ahead of Brexit Day.

*A Conservative Right To Vote campaign for a second EU referendum was launched by MP Phillip Lee, who claimed support for a so-called People's Vote was "growing fast" among his colleagues on the Tory benches.

*Lord Hannay, the former UK ambassador to the UN, warned the 300-year-old Union faced a "rough ride" post-Brexit, arguing that ignoring Remain votes in Scotland and Northern Ireland was a "majoritarian supremacy" that had fuelled calls for Scottish independence and a united Ireland.